Nothing in the steering wheel's horn circuit is switched via the ignition circuit. It's fed by an ALWAYS HOT circuit. Are you checking it via the steering wheel pad or using the PANIC button on your remote?

The cruise control failure might be due to a common failure, might be something else.

Steve

 

I checked using the steering wheel pad and it works with ignition off only, soon as key is turned horn stops working.

Tim

 

Just got thru checking horn with key turned to accessories and it works using the steering wheel pad. Horn stops working when key is turned to on. Also with engine running horn will not work.

Tim

 

Where can I find the Pinpoint Test E1 procedure? Do I need the service manual?

 

Yes. Send me your email address via PM and I will send you the proper excerpt from the manual.

Include your vehicle identification so I can access the correct documentation.

Steve

 

Tim,

Here is the schematic of the horn circuit.





Your problem is quite unusual. Nothing in this circuit is supposed to be switched by the ignition switch...

I'd suggest checking the following to see if we can zero in on the fault.

1. Verify whether fuse F7 is HOT in both OFF and RUN. It should be.

2. Pull the horn relay.
A. Check for any voltage at pin 1 in both the OFF and run positions . Shouldn't be any (zero volts). If correct, proceed to step B.
B. Check for resistance to ground at pin 1. Should be zero ohms whether in START or RUN only when the horn pad is pressed.

Let me know what you find.

Steve

 

PM sent!

Thanks.

 

Steve.

Thanks for the information. I plan to check the horn this weekend to see if I can find what is wrong. New twist to the problem, when I press the brake pedal down the horn will not work at all using the steering wheel pad. I did not try the panic button. A little history, I bought the truck new, it has not been in an accident nor had any major work done to it. It has power windows, outside mirrors and power adjustable pedals, no other power options.

Thanks again
Tim

 

Steve,

Update on my horn/cruise control problem. My son traced it down to the speed control unit in the engine compartment. It shorted out due to the brake control switch for the cruise control. This was totally my fault, I delayed taking the truck in for the recall and this was the result. We replaced the speed control unit and the plug, now everything works as it should, horn and cruise. Thanks for you help.

Tim

 

That's a pretty interesting result. Thanks for following up.

Steve

 

BUMP

Just like to know exactly what was replaced to solve this issue as I believe I have the same problem.

 

From the post above it was recall 05S28 ( Speed Control Deactivation Switch ).
This is fixed for free at the dealer, the part number is 1L1Z-9F924-AA

 

Is that the common cruise control recall? If so, I've already had that done. What is the speed control unit? I'm thinking it's the unit that controls the throttle cable when the cruise is on, unfortunately that part is only available through the dealer. Also is the plug he referred to the plug going into the speed control unit?

 

Yes that is the recall, don't forget there is a fuse in the harness that could also be blown.

How about running the CC test ?

Self-Test Diagnostics

WARNING:
This test is a key on engine off (KOEO) test only that is conducted in park only with emergency brake fully engaged.

1. Enter self-test diagnostics by depressing the speed control OFF switch while turning the ignition key ON, making sure the engine does not start and is not running. The speed control indicator on the instrument panel will flash once to indicate that speed control module entered the diagnostic mode. Five additional flashes at this point indicate a defective speed control servo. Release the OFF switch.

2. Press the remaining switches in this sequence: ON, RESUME, COAST and SET/ACCEL.

If the ON switch is not depressed within five seconds after entering the diagnostics mode, the module times out and the procedure must be started over.

The speed control indicator lamp will flash as each switch is depressed. Press each switch in the sequence immediately after the indicator light goes out for the previous switch.

Note:
There will be a slight delay when the last button is pressed and the lamp flashes.

3. A lamp flash with the last button (SET/ACCEL) indicates that the static test passed. If the lamp does not flash with the last button and there are no additional flashes of the lamp, the switch is defective.

If the lamp does not flash with the last button, and additional flashes occur, follow the chart below for trouble codes:

— 2 flashes - BPP defective, circuit is defective, brake applied, CPP switch or jumper (if equipped).

— 3 flashes - deactivator switch is open or circuit defective.

— 4 flashes - vehicle speed signal is out of range or circuit is defective

4. Immediately (.25 second delay) after the static test, the speed control servo does a dynamic test by automatically actuating the throttle lever from 8 mm (0.315 in) to 12 mm (0.472 in) of travel from the idle position. During the dynamic throttle pull, observe throttle movement to witness any binding or sticking of the speed control cable and correct connection of speed control cable to throttle lever. Make sure the throttle returns to the idle position.

5. Return the ignition switch to the OFF position and proceed to the Symptom Chart.

 

I was going to do that test until I realized that the bulb for my cruise control is out. Of course I learned to do the I/P bulb test only hours after finishing the intermittent odometer repair on my I/P. As soon as I find some time to tear into the dash again I'll replace the bulb and then perform the CC test.